QUATERNARY DEPOSITS ALONG THE INDUS SUTURE ZONE AND EVOLUTION OF HIMALAYAN RIVERS

Quaternary deposits, found only in isolated basins behind the main gre at Himalayan crest-line and along the courses of the main rivers, are preserved only in isolated structural depressions scoured by valley gl aciers because of rapid Quaternary uplift and attendant erosion. The E arly Quaternary deposits rest unconformably on basement and are preser ved only in the Chilas and Skardu areas of Baltistan, where they consi st of a basal till overlain by fining upwards valley fill sequences. P alaeomagnetic reversal correlation suggests an earliest Pleistocene ag e. The Middle Pleistocene deposits seem to be abs-ent. The early Pleis tocene (or pre-Quaternary) is overlain at Leh and elsewhere, by a comp lex of tills and terraces associated with possibly the last three main glacial phases of the Late Pleistocene. The Quaternary events cannot ordinarily be disentangled from earlier Pleistocene events. Correlatio n is very difficult due to the isolation of most exposures and the lac k of dateable sections.